Sure!
To make this more helpful, it'd sure be nice to know what year that truck is!
You've got 60k, so I guessed it's about 5 years old. All the searches I did apply to the 1999 models.
Here is a list of cheap upgrades that add small amounts of power.
I mean small. Hopefully they add up enough for you to feel it.
I attempted to make this list starting with cheesy-easy and going down to harder.
1. Make sure the engine is in tune.
Make sure the tires are inflated properly, etc.
2. Change the plugs.
Bosch Platinum Plus 4's are nice. So are Splitfires. Personally, I trust the Platinums. Your local auto parts store has them both. Get some nice plug wires too.
3.
Buy a K&N air filter. That will improve airflow.
4. Make sure your fuel injectors are clean. Run a bottle of fuel system cleaner through. Cheap bottle of Chevron fuel cleaner with Techron should do it. Pour in gas tank, drive car. Done.
5. Have a low-backpressure exaust intalled. It won't be cheap, but hey, a nicely done high performance exaust has got to be worth 5-15hp.
6. Find a performance chip for your truck. For this WE MUST know the year. Often the use of a chip will require premium gas. Basically they advance the timing and play with the fuel delivery curve.
7. Look for a bigger throttle body. Install it.
8. Find a higher performance cylinder head. Install that. (You will not find one for that engine, let's move on...)
9. Lose some weight on the truck. Is the bed full of shit? Empty it. Look into buying fiberglass or carbon fiber body panels. Replace the hood. Strip all the soud deadening out of the truck. Throw out the stereo, AC, passenger seat. It's your call, and the sky's the limit...
10. Buy alloy wheels, that might shave 15lbs a wheel.
In short:
Make sure the engine, and truck, are in proper shape.
Now you're looking at plugs, an airfilter, maybe an air inake tube, and an exaust.
Then you're done with that engine.
Unless you're going to install NOS? That'll help...but NOS is not condusive to an engine living to 150k.
There is very, very little you can do. If you do the plugs, plug wires, air filter, exaust, and chip, I (realistically) see maybe, MAYBE 15-30hp.
There are plenty of people who are out to take advantage of people in your situation by promising 20-30% hp increases. "GET 25hp with our air filter!"
Yeah, that's all bullshit.
There's very little you can do with that engine. I found no chips for it, no heads, no headers, no high flow cats, no nothing. It's not the engine people choose to modify, so there's no market in making parts for it.
If I can possibly help more, please don't hesitate to PM me.